Heretofore, the Sonogashira reaction has widely been known as a coupling reaction of an alkyne and has been used in a synthesis of a biologically active substance having an acetylene skeleton in the molecule, or an organic functional material.
In this Sonogashira reaction, palladium as a catalyst and copper as a promoter are usually used in combination. In practice, for example, tetrakis(triphenylphosphine)palladium, dichlorobis(triphenylphosphine)palladium and copper iodide are used in combination (see, for example, Japanese Unexamined Patent Publication No. Hei 10-114691).
However, since palladium is expensive, it is desired that palladium is recovered after the reaction and used again so as to reduce the production cost.
However, in the actual reaction, palladium is used in the form of an organic metal complex, which is soluble in an organic solvent, such as tetrakis(triphenylphosphine)palladium or dichlorobis(triphenylphosphine)palladium, as described above. Therefore, it is difficult to recover palladium and the organic metal complex is discarded as it is after the reaction.
An object of the present invention is to provide a catalyst for synthesis reaction which can achieve good yield in the Sonogashira reaction and also can be recovered after the reaction, and a method for synthesizing a compound in which the catalyst for synthesis reaction is used.